1. Field of the Invention
This invention relates to the field of nuclear cardiology in medical diagnosis. In nuclear cardiology, a patient's heart function is evaluated by monitoring of radiation from, one for example, heart chamber, following the administration of a radioactive tracer into the patient's cardiovascular system. A scintillation camera is used to detect, and indicate location of, radiation events within the patient's heart caused by the presence of the tracer in his blood.
Data processing apparatus is used to develop information regarding the patient's cardiac function from the pattern of variation of radioactivity from the inspected region of interest, which may, for example, be selected as defining the patient's left ventricle. This time varying pattern of radiation describes volumetric time variation of blood in the inspected chamber. From this information, a curve describing the chamber's time varying volume can be derived. Calculations incorporating the minimum and maximum volume can be made which describe the fraction of blood within the chamber which is pumped by the heart in the course of each beat. Specifically, the ejection fraction, or EQU E.F.=D-S/D
where D is the end diastolic volume of the heart chamber and S is the end systolic heart chamber volume.
2. Description of the Prior Art
It has been proposed to implement the above described nuclear cardiology diagnostic technique by the use of an electronic data processing computer in conjunction with a scintillation camera and an electrocardiogram apparatus. In accordance with this proposal, an investigator injects a quantity of radioactive tracer material into the patient's cardiovascular system. When the radioactive tracer material has reached the heart, analog signals from the scintillation camera, indicating the location of nuclear radiation events within the patient's body over a time period, are digitized. This digitized location information is recorded in its entirety in the computer memory. The computer is programmed to subsequently scan this information, and to isolate therefrom information describing radiation events emanating from a particular zone of the patient's body.
The computer of such a proposed system is programmed to analyze the selected data from the predetermined zone to derive information relating to heart function. In doing this, the computer subdivides the stored information into a series of portions, each portion corresponding to radiation occurring during a particular time segment. The information, thus time divided, is then analyzed by computational manipulations of the computer to produce a representation of a curve describing the time varying volume of radioactively traced blood in the studied heart chamber.
While such a system affords utility in medical diagnostic examinations, it requires highly complex and expensive apparatus for operation. The requirement for an electronic data processing computer is an obvious example of this very considerable expense the complexity. The computer must have sufficient memory capability to incorporate a large amount of stored information. The proposed system must store the entirety of radiation location indicating information prior to the beginning of analysis upon it. This slows system operations since it requires analysis of the stored data to await the completion of the storage operation before it can proceed.
Accordingly, there has existed a desire for a relatively simple and inexpensive system for performing specific diagnostic routines in nuclear cardiology, such as ejection fraction calculation, left ventricular ejection time, and left ventricle integrated time activity curve analysis.